Otto Robert Frisch

Otto Robert Frisch (1904-1979)

Otto Robert Frisch was born October 1, 1904, in Vienna. The son of a painter and a concert pianist, he had inherited his aunt Lise Meitner‘s love of physics, graduating from the University of Vienna in 1926 with some work on the effect of the newly discovered electron on salts. After some years working in relatively obscure laboratories in Germany, Frisch obtained a position in Hamburg under the Nobel Prize-winning scientist Otto Stern. Here, he produced novel work on the diffraction of atoms (using crystal surfaces) and also proved that the magnetic moment of the proton was much larger than had been previously supported.

Frisch first worked at the universities of Berlin and Hamburg, but was dismissed under German racial laws in 1933 and moved to the Institute for Theoretical Physics in Copenhagen. The accession of Adolf Hitler to the chancellorship of Germany that same year made Frisch decide to move to London, where he joined the staff at Birkbeck College and worked on cloud chamber technology and artificial radioactivity. He followed this with a five-year stint in Copenhagen with Neils Bohr, where he increasingly specialized in nuclear physics, particularly neutron physics.

In December 1939, Lise Meitner, who was living in exile in Stockholm, informed the visiting Frisch that Otto Hahn and Fritz Strassmann had found the phenomenon that strongly suggested the nuclear fission of uranium by bombardment (slow) neutrons. Hahn and Strassmann in Berlin had discovered that the collision of a neutron with a uranium nucleus produced the element barium as one of its byproducts. Frisch and Meitner explained the process in terms of excessive electrical charge, estimated the energy released and coined the term “fission” to describe it. Frisch returned to Copenhagen, where he was quickly able to isolate the fragments produced by fission reactions.

In the summer of 1939, Frisch left Denmark for what he anticipated would be a short trip to Birmingham, but the outbreak of World War II precluded his return. Working with the physicist Rudolf Peierls, he demonstrated that the fissioning of uranium had the potential to create a volatile chain reaction which, when using uranium-235, could be used to develop an extremely destructive weapon.

Frisch had been left out of the research because his foreign status posed a security risk. In 1943, along with many other scientists that had been exiled from Germany, Frisch was naturalized as a British citizen, and was permitted to work for the Manhattan Project as part of The British Mission. There he was head of the Critical Assembly Group.

After the war, Frisch returned to England to work for the Atomic Energy Research Establishment at Harwell and held the Jackson Chair of Physics at Cambridge from 1947 to 1972, when he retired to concentrate on his books and business interests. He died on September 22, 1979, in Cambridge, England.